Prostate cancer (PCa) disproportionally affects African American men (AA) who have 60 percent higher incidence rate and twice the death rate of Caucasian men (CA), and is the second leading cause of cancer- related deaths in AA men probably due to a more aggressive disease. While socioeconomic factors contribute to this health disparity, they do not fully explain the differences in prostate cancer incidence, aggressiveness, and mortality among different ethnic groups. Non-coding RNAs, especially, miRNAs have emerged for their important gene regulatory function and their roles in regulating multiple coding genes and thereby modulate several biological pathways including cell proliferation, differentiation, apoptosis, metastasis and angiogenesis. Recent studies have identified distinct miRNA expression in serum of cancer patients and have suggested their usefulness as molecular targets and as biomarkers to predict progression from preneoplasia to cancer and outcome/prognosis of cancer patients. Very little is known about racial differences in the expression of these miRNA in cancers like prostate cancer that disproportionally affect AA men. Based on our preliminary data, we hypothesize that miRNA dysregulation in serum might be associated with PCa progression and PCa health disparities with potential to be developed as molecular target(s) and minimally invasive biomarker(s). The specific aims are: (1) Study the expression of miR-101, miR-25 and miR-628-5p in prostate cancer where we will compare the expression of these miRNAs in (a) serum from 50 AA and 50 CA and (b) tissues from 50 AA and 50 CA prostate cancer patients by Q-PCR. (2) Examine the effects of miR-101, miR-25 and miR-628-5p gain- and loss-of-function on the neoplastic phenotype of prostate cancer and their oncogenic activity in normal prostate cells. This proposal will (i) establish a basis to study the expression pattern of these miRNAs in diverse serum samples and (ii) generate preliminary data for continued mechanistic investigation of miRNA biology in prostate cancer health disparities. Our future studies will validate these miRNAs in a wider population and examine the involvement of these miRNAs in the tumor biology of AA prostate cancer.